Firearm with sintered metal chamber



y 4 1 7 J. c. HARTLEY 2,791,856

FIREARM WITH SINTERED METAL. CHAMBER Filed Jan. 6, 1954 Hal 23 {*3 //2I F2 25 INVENTORZ JAMES C. HARTLEY ATTORNEY United States Patent FIREARM WITH SINTERED METAL CHAMBER James C. Hartley, Branford, Conn., assignor to Olin Mathieson Chemical Corporation, a corporation of Virginia Application January 6, 1954, Serial No. 402,561

Claims. (Cl. 42 -76) This invention relates in general to firearms and more particularly to the cartridge receiving chamber of a firearm.

In the operation of cartridge-loaded firearms, difficult extraction of the fired cartridge case frequently occurs. This difficult extraction may be attributed to the fact that upon firing, all the explosive pressures are exerted on the cartridge case only from within, thereby tending to expand or obturate said case, and forcing it into intimate contact with the chamber walls. This is particularly true in automatic firearms wherein the design of the chamber is such that the degree of obturation may exceed the elastic limits of the cartridge case material. In such case, plastic deformation of the cartridge case occurs, forcing the walls of the case into intimate contact with the chamber walls and permitting it to fill any irregularities in the chamber, thus rendering removal of the case from the chamber extremely difiicult.

One attempt at remedying this undesired condition is seen in U. S. Patent 898,908 issued September 15, 1908. This patent discloses a special chamber having channels drilled therein which direct the gases of explosion from the bore in front of the case to the space surrounding it thereby substantially equalizing pressure within and Without the case. In practice, however, this chamber is not suitable for commercial exploitation as it involves a complicated production technique.

An object of this invention, therefore, is an improved cartridge receiving chamber of a firearms barrel which avoids distortion of its contained cartridge case when fired. Another object of this invention is the production of the aforementioned improved chamber by a relatively simple production technique. Still-another object of this invention is the production of a gun having an improved chamber which is easily repairable when damaged.

F It has been found in accordance with this invention that by constructing a cartridge receiving chamber of a firearm of fluid pervious material there results an improved firearm which avoids cartridge extraction diiliculties. Fluid pervious for the purposes of this invention may be defined as any material which allows fluids such as gases or liquids to flow through the body when the pressure behind such fluid is in the range of about 200 pounds per square inch or greater. This fluid pervious material, which may be constructed of any suitable material having the requisite tensile strength for containing an explosion, such as for example, a sintered metal liner, is placed so that it envelops the forward end por' tion of the chamber enclosed cartridge case and extends rearwardly to a point on the body of the case which preferably is the point where the walls thicken to form the I igniter end. The rear portion of the chamber, more aptly and travel rearwardly to the gas impervious material. By so doing they surround the cartridge case and, therefore, the pressure within the cartridge case and surrounding the cartridge case is thereby substantially equalized. While the desired obturation occurs, no plastic deformation causing diificult extraction of the cartridge case thereby results.

The foregoing objects and advantages will be more clearly understood by reference to the following detailed description and accompanying drawing illustrating typical embodiments of the invention, in which Figure 1 shows a planar longitudinal sectional view of a firearm barrel containing one form of a liner encompassed by this invention and showing a cartridge at an instant just after firing,

Figure 2 shows a planar cross-sectional view of the improved chamber taken on line 2-- of Figure 1,

Figure 3 shows a planar cross-sectional view, of the improved chamber taken on line 3'3 of Figure 1, and

Figure 4 is a planar longitudinal sectional view of the liner or fluid pervious member to be inserted into the counterbored cavity of the firearm barrel.

In Figure 1 there is shown a firearm 11 containing a barrel 13 and breech member 14. In the barrel there is a bore 15 with rifling 16. The breech member of the gun has been counterbored and contains a cavity, the inner surface of which is numbered 17. This inner surface of the cavity may be partly fluted for the length of the fluid pervious liner for assisting in the dissipation of explosive gases throughout the voids of said fluid pervious liner hereinafter described. Conversely the outer surface of the fluid pervious liner may also be fluted. Within this cavity is contained a fluid pervious sleeve liner 18, held in place by an outer fluid impervious liner 19 which is shown threaded at 20. Within these liners is contained a cartridge case 21 which is shown a moment after it has been fired causing bullet 22 to travel down the bore of the gun. Liners 18 and 19 may consist of either of 2 liners of which the outer fluid impervious liner 19 acts as the retaining means for keeping fluid pervious liner 18 in place or else of one integral liner of which 18 denotes the fluid pervious portion and 19 denotes the fluid impervious portion. These liners are preferably kept in position by threading the fluid impervious liner or section to the inner Wall of the counterbored cavity at 20. By this method an easily-repairable firing chamber may be produced. However, other methods of aflixation, such as welding, sweating, etc., may also be used depending upon the needs of the situation.

Where required, a solid liner or tubular member 26, contained within a fluid pervious liner, as shown in Figure 1, may be used. This liner is for the purpose of preventing the lip of the cartridge case from overduly expanding into the fluid pervious liner and thereby again causing extraction difliculties. It may be constructed of any material of suflicient tensile strength to avoid this undue expansion of the lip of the case. Its length and thickness, of course, depends upon the needs of the situation. For example, where the case has a great tendency at its lip to expand with great force a liner, of suflicient thickness and length must be used. Where the lip does not expand at all or only with very little force the liner 26 may either be omitted or else be of very narrow wall thickness.

To operate the gun, bolt 23 has been closed and firing pin 24 actuated to strike the primer of cartridge 21. The type of bolt used is obviously immaterial for the purpose of this invention and may either be of the center fire type or of the rim fire type. Here again other means of ignition such as electrical ignition would not affect the advantages obtained by this invention and should, therefore, be considered immaterial.

Figures 2 and 3 disclose a cross sectional view of the firearm shown in Figure 1.

Figure 4 discloses a liner that may be used in this invention. It is of the integral type having fluid pervious section 18 and fluid impervious section 19 threaded at 20. Again where necessary, a liner 26 as in Figure 1, may be incorporated into this liner. It is to be noted that the fluid pervious liner may also be in longitudinal arc sections or similar subdivisions for easy insertion into the counterbored cavity. It may also have its outer surface fluted or channeled to aid in dissipating the explosion fluids.

Under operating conditions, the cartridge is inserted into the improved chamber and the bolt is closed and the cartridge fired. Upon firing, the bullet 22 emerges from the cartridge case 21.. As soon as this occurs, the explosive gases 25 by reason of their high pressure, flow through the voids of the fluid previous liner thereby impinging the outside of the cartridge case. Where the inner wall of the counterbored cavity has been fluted, gas dissipation throughout the voids is even more easily facilitated. The gases, however, are prevented from blowing rearwardly by reason of fluid impervious liner 19. Since only part of the high pressure emplosive gases are able to surround the cartridge case the necessary obturation of the case occurs but there is no undue plastic deformation. Therefore, extraction of the case from the chamber may be performed with little difliculty and a smooth operation of the semi-automatic or automatic gun results.

In constructing the improved chamber shown in the drawing the following procedure may be used. However, it is to be specifically understood that other obvious procedures exist and are, therefore, to be construed as being within the teachings of this disclosure.

The chamber section of a barrel is counterbored to an inside diameter suflicient to permit insertion of a fluid pervious sleeve. This counterbored cavity chamber is fluted at its forward end to facilitate dissipation of the explosive fluids throughout the voids. It is threaded at its breech end to receive an outer fluid-impervious threaded liner. A gas pervious liner made as outlined below is then inserted into this counterbored cavity and held in place by threading into place an outer fluid impervious liner. Again it should be here stated that other methods or combinations of affixation may also be used.

The fluid pervious liner may be made by various techniques well known to the art. One of these, in which a metal liner is made, utilizes a powder metallurgical technique; namely, forming a liner of powdered metal and sintering under appropriate heat and pressure for a definite length of time. Another method involves the turning a metal wire of appropriate size upon a mandrel and sintering the formed bobbin of metal wire. The degree of permeability that results depends upon the number of turns, the size of the wire used, and the amount of pressure used upon the structure during the winding operation and the amount of mechanical deformation after sintering. Where necessary and appropriate, depending upon the bobbin forming operation, the fluid pervious liner may have to be machined so as to fit tightly within the counterbored cavity and to properly hold and obturate a cartridge case within its own cavity.

The fluid pervious material may be formed of any material with the requisite strength and durability required for construction of rifle chambers, particularly good examples being steel, Stellite alloys, molybdenum and ceramic-metallic combinations.

The material should preferably be fluid pervious to p the extent of permitting pressure fluids in the range of 200 pounds per square inch and above to flow through it 2,791,856 6 H 7 v .r"

with only slight difliculty. The thickness of the lining andthe circumferential area of the cartridge case that it should envelop depends upon the degree of obturation during firing that is required, the degree of permeability of the material being used, as well as the pressure of explosive fluids encountered. It may be generally stated that the fluid pervious member should preferably envelop the circumferential area of the cartridge case rearwardly to a point substantially where no plastic deformation occurs such as where the'walls of the case'substantially thicken to form the igniter end. The thickness of the lining should preferably be in the order of oneeighth of an inch on upward as the caliber of the gun increases. Obviously no exact fixed length or thickness can be given to fit all guns for each gun has different ballistic characteristics.

While a detailed description of the invention has been provided, it is realized that those skilled in the art may make various modifications in the described device without departing from the spirit and scope of this invention.

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is as follows:

1. In a firearm, the improvement which comprises a barrel-chamber lined at its forward end with a fluid pervious material, said fluid pervious material comprising sintered metal.

2. In a cartridge-loaded firearm, the improvement which comprises lining the chamber of the weapon with a sintered metal liner of fluid pervious material extending from a point in front of the mouth of the cartridge case rearwardly to a point where it will counteract plastic deformation of the case, said liner being retained within the chamber by means of a substantially fluid impervious liner fastened to the inner side of the breech end of the chamber.

3. In a cartridge-loaded firearm the improvement which comprises lining the chamber of the weapon with a liner of fluid pervious material extending from a point in front of the mouth of the contained cartridge case rearwardly to a point where it will counteract plastic deformation of the case and being retained within the chamber by means of a substantially fluid impervious liner fastened to the inner side of the breech end of the chamber, said fluid pervious liner being formed with an annular cavity having a separate tubular member within said cavity, said member substantially surrounding the forward lip of the cartridge case to prevent undue lip deformation of said case into the fluid pervious material.

4. A cartridge-loaded firearm having a cartridge chamber lined with a fluid pervious sintered metal material at its forward end and a fluid impervious metal material at its breech end.

5. A cartridge-loaded firearm having a fluted counterbored cartridge chamber lined with a liner of fluid pervious sintered metal at its forward end, said sintered metal being steel and a liner of fluid impervious metal at its breech end.

References Cited in the file of this patent UNITED STATES PATENTS 898,908 Mertens Sept. 15, 1908 1,687,780 Neale Oct. 16, 1928 2,589,945 Leduc Mar. 18, 1952 FOREIGN PATENTS 4,095 Switzerland Sept. 28, 1891 548,102 Germany Apr. 7, 1932 603,190 Germany Apr. 26, 1935 259,488 Switzerland June 16, 1949 

1. IN A FIREARM, THE IMPROVEMENT WHICH COMPRISES A BARREL-CHAMBER LINED AT ITS FORWARD END WITH A FLUID PERVIOUS MATERIAL, SAID FLUID PERVIOUS MATERIAL COMPRISING SINTERED METAL. 